Construction continues on the Biomarin building along Lincoln Avenue and Second Street in San Rafael. The project consists of a three-story, research and development facility and a parking garage. Alan Dep — Marin Independent Journal

A worker walks through the framework of the new Biomarin building being constructed on Lincoln Avenue and Second Street in San Rafael. Alan Dep — Marin Independent Journal

If you’re on Highway 101 during the next few months and happen to see a truck carrying 55-foot slabs of concrete, chances are the driver is headed for BioMarin Pharmaceutical Inc.’s expanded downtown San Rafael campus.

It’s been nine months since BioMarin broke ground on its expanded facility and new six-story parking garage at the San Rafael Corporate Center on Lindaro Street — and construction is progressing quickly. Both the parking garage and the company’s new laboratory are anticipated to be done by the end of the year.

The biopharmaceutical developer, which specializes in the development and production of medications that treat rare diseases, purchased the corporate center for $116.5 million last year from Seagate Properties after leasing space in the center since early 2012.

Debra Charlesworth, a spokeswoman for the company, said construction workers are creating a new three-story, 85,000-square-foot research and development facility at 791 Lincoln Ave. and a parking garage with 649 spaces at 788 Lincoln Ave.

“We’re thrilled that we’re able to build more in San Rafael and grow as a company. We’re proud of the work we’re doing for patients with rare diseases,” Charlesworth said.

Jim Redenbarger, principal project manager, said now that the foundation of the parking lot is complete, it’s time to start the concrete work and make places for cars to park.

“Now we’re starting to pour the concrete slabs or decks and we will probably be doing that for the next three months,” Redenbarger said. “It’s going to look nice and look like the other buildings. It’ll be very tasteful.”

Charlesworth said 10 to 20 solar panels will be placed on the roof of the garage and the garage will include electric vehicle charging stations. She said the plan is to make the garage as aesthetically pleasing as possible.

“We’re investing in making that look very nice,” she said. “It will have ornamental iron and even the sides will give the appearance of windows as opposed to a parking garage.”

Redenbarger said the research and development facility is covered in scaffolding right now, but will start to look more finished as the 55-foot concrete slabs go up.

“The exterior will be done late in the summer,” he said, adding the building is being constructed to California’s green building codes.

Nearly 400 BioMarin employees work out of the corporate center and the expansion will allow for an additional 300 employees to work downtown. In addition to its headquarters in San Rafael, it maintains manufacturing operations in Novato. The company employs about 1,300 people and could employ more as the company continues to grow.